This weekend I explored the Stillwater River and West Rosebud. Three hours away it turns out. Worth it.
The giant lake at the bottom is called Mystic Lake, which is a semi-natural body of water that feeds a hydroelectric station. The little dam you can see was constructed to raise the lake level 12 feet, making the impressive lake just a little deeper for greater power generation. In the photo with the pipe and tracks what you are looking at is not a giant roller coaster, but the tram for pipe maintenance and such. The pipe itself carries water from the lake to the hydroelectric generator, and such a drop creates a whole lot of power from just a little water. The building you see was built in 1924 and has stood the test of time quite well.